As Katie and Lok set to go off along the river to search for
other fruit, Gara warns them about Fangar, who prowls the area,
matched only by Tanga. Lok explains that
Tanga is what John refers to as an Allosaurus and Katie
deduces that Fangar must be a Tyrannosaurus rex. Fangar
is the Tyrannosaurus referred to in the title of the
story.

Possibly the fight between the T. rex and the
Allosaurus here was inspired by the quarrels that took
place in a couple of
Land of the Lost
episodes between Grumpy and Big Alice!